/Engine/Source/Runtime/InteractiveToolsFramework/Public/ToolTargetManager.h
Looks through the currently selected components and actors and counts the number of inputs that could be used to create qualifying tool targets.
virtual void EnumerateSelectedAndTargetableComponents ( const [FToolBuilderState](API\Runtime\InteractiveToolsFramework\FToolBuilderState) & SceneState, const [FToolTargetTypeRequirements](API\Runtime\InteractiveToolsFramework\ToolTargets\FToolTargetTypeRequirements) & TargetRequirements, [TFunctionRef](API\Runtime\Core\GenericPlatform\TFunctionRef)< void([UActorComponent](API\Runtime\Engine\Components\UActorComponent) *)> ComponentFunc ) const